nums = [0,1,2,3]

nums.sort()
if nums[-1] != len(nums):
    print(len(nums))
else:
    for i in range(len(nums)):
        num = nums[i-1] + 1
        if nums[i] != num:
            print(num)

print("更新")
print("笨蛋笨蛋，嘻嘻嘻")